LibWebView: Prevent quoting attribute values twice in the Inspector

As of commit ccd701809fc168c90b2f74bdb3b3f2a3fd82d10e, the formatter for
JsonValue now fully serializes the value. The serializer will surround
the string value with quotes. We want control over when we add quotes to
the generated Inspector HTML, so avoid formatting attributes as raw JSON
values.

Userland/Libraries/LibWebView/InspectorClient.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ * Copyright (c) 2023-2024, Tim Flynn <trflynn89@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -523,11 +523,13 @@ String InspectorClient::generate_dom_tree(JsonObject const& dom_tree)
 
         if (auto attributes = node.get_object("attributes"sv); attributes.has_value()) {
             attributes->for_each_member([&](auto const& name, auto const& value) {
+                auto value_string = value.as_string();
+
                 builder.append("&nbsp;"sv);
-                builder.appendff("<span data-node-type=\"attribute\"  data-tag=\"{}\" data-attribute-name=\"{}\" data-attribute-value=\"{}\" class=\"editable\">", tag, name, value);
+                builder.appendff("<span data-node-type=\"attribute\" data-tag=\"{}\" data-attribute-name=\"{}\" data-attribute-value=\"{}\" class=\"editable\">", tag, name, value_string);
                 builder.appendff("<span class=\"attribute-name\">{}</span>", name);
                 builder.append('=');
-                builder.appendff("<span class=\"attribute-value\">\"{}\"</span>", value);
+                builder.appendff("<span class=\"attribute-value\">\"{}\"</span>", value_string);
                 builder.append("</span>"sv);
             });
         }